Method for e3nhanced delivery of oxybutynin and compositions thereof

ABSTRACT

This invention provides to a method for enhancement of systemic delivery of oxybutynin by administration via the nasal route, and methods of treatment comprising intranasal administration of oxybutynin. The present invention further provides pharmaceutical compositions comprising oxybutynin and/or pharmaceutically acceptable salts thereof.

[0001] This application claims the benefit of U.S. provisionalapplication No. 60/229,107 filed Aug. 30, 2000, the disclosure of whichis hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to compositions for enhancement ofdelivery of oxubutynin, antimuscarinic and spasmolytic drugs, byadministration via the nasal route to treat patients suffering fromoveractive bladder with symptoms of urinary urgency, frequency or urgeincontinence. The invention is also directed to methods of treatmentthereof, and methods of preparation thereof.

[0004] 2. Description of the Related Art

[0005] U.S. Pat. No. 6,039,967 to Ottoboni, describes an intravesicaldrug delivery system for placement of oxybutynin into the bladderthrough the urethra.

[0006] U.S. Pat. No. 5,840,754 to Guittar, describes the administrationof a controlled-release dosage form tablet comprising oxybutynin tolessen the incidence of side effects.

[0007] U.S. Pat. No. 5,736,577 to Aberg, describes the use of opticallypure (S)-oxybutynin for treating urinary incontinence.

[0008] U.S. Pat. No. 5,674,895 to Guittard, describes a rate-controlledtablet dosage form of oxybutynin.

[0009] U.S. Pat. No. 5,500,222 to Lee, describes the transdermaladministration of oxybutynin together with a suitable permeationenhancer.

[0010] Oxybutynin, [Benzeneacetic acid,a-cyclohexyl-a-hydroxy-4-(diethylamino)-2-butynyl ester], a tertiaryamine with antimuscarinic, spasmolytic and local anesthetic properties,is currently used for the treatment of overactive bladder with symptomsof urinary urgency, frequency or urge incontinence due to detrusorinstability or detrusor hyperreflexia. Oxybutynin is currently marketedin the United States under the trade names Ditropan and Ditropan XL asan oral dosage form (Physician's Desk Reference, pp 507, 54^(th)Edition, 2000).

[0011] After oral administration of oxybutynin, low systemicbioavailability (<6%) is observed because of extensive first-passmetabolism (Douchamps et al., Eur. J. Clin. Pharmacol. 35:515, 1988).Oxybutynin is metabolized in the liver and it has been suggested thatthe metabolite N-desethyloxybutynin, is pharmacologically active(Lindeke et al., Biomed. Mass. Spec. 8: 506, 1981; Aaitonen et al., ActaPharmacol. Toxicol. 55: 100, 1984) and is associated with the systemicside effects following oral treatment with oxybutynin (Buyse et al., J.Urology 160:892, 1998). Measurements of oxybutynin andN-desethyloxybutynin plasma levels after oral administration ofoxybutynin resulted in a considerably larger (5 to 11 fold)concentration of the metabolite compared with the parent compound(Hughes et al., Xenobiotica 22: 859, 1992). Functional and receptorbinding experiments have also demonstrated that N-desethyloxybutynin hassimilar anticholinergic activity to the parent compound on isolatedhuman bladder and parotid gland (Waldeck et al., J. Urology 157: 1093,1997). Despite the clinical success of intravesical oxybutynin, theexact mechanism of action remains unknown. As systemic side effects weregenerally absent when the drug was applied intravesically (Buyse et al.,J. Urology 160:892, 1998), it has been suggested that oxybutynin was notabsorbed into the blood stream and that its efficacy resulted from aprofound local effect alone. Measurements of plasma levels of oxybutyninafter intravesical and oral administration revealed extensiveinter-individual variations, but clearly there was substantialabsorption of the drug after intravesical application and therefore itseffect on detrusor muscle was believed to be mainly systemic due to itsabsorption (Madersbacher and Jilg, Paraplegia 29: 84, 1991; Massad etal., J. Urology 148: 595, 1992; Madersbacher and Knoll, Eur. J. Urology28: 340, 1995). Although no measurements of circulating metabolites wereperformed in these studies, it has been speculated that a difference inmetabolite concentration, due to reduced first pass metabolism, couldexplain the difference in systemic side effects. Alternatively, theremight be a different metabolism after oral administration, compared withintravesical instillation, due to enzymatic reactions in the alimentarytract. In contrast to the promising clinical results of intravesicaloxybutynin therapy, patient withdrawal was significant (up to 65%) inseveral studies, mainly due to practical inconvenience and, to a lesserextent, untoward effects (Kasabian et al., J. Urol. 151: 944, 1994;Connor et al., J. Urol. 151: 1045, 1994; Palmer et al., J. Urol.157:638, 1997). Hernandez et al. concluded that the only disadvantage tointravesical therapy appeared to be variable long-term patientcompliance (Hernandez et al., J. Urol. 152:1582, 1994).

[0012] Among the adverse effects of oxybutynin following oraladministration include dry mouth, constipation, diarrhea, nausea,vomiting, somnolence, dizziness, headache pain, insomnia, tachycardia(Physician's Desk Reference, pp 507, 54^(th) Edition, 2000; DrugInformation, AHFS 99: pp. 3164, 1999). In clinical studies, adversereactions requiring discontinuance of oxybutynin therapy (5 mg 3 timesdaily) occurred in about 20% of patients.

[0013] Therefore, in view of the aforementioned deficiencies attendantwith prior art compositions and methods of oxybutynin administration, itshould be apparent that there still exists a need in the art for a safeand convenient composition and method for administering oxybutynin topatients at safe and effective doses. To the best of applicants'knowledge, nasal administration of oxybutynin is unknown and completelyunsuggested by the art.

[0014] While nasal administration has become an accepted route ofadministration, the following disclosures limit that mode of delivery tospecific drugs described. Moreover, it has been observed that manytherapeutic agents cannot be usefully administered by this unusualroute. Consequently, nasal administration remains a technique for whichapplicability is far from universal and the results unpredictable.

SUMMARY OF THE INVENTION

[0015] Accordingly, a major object of the present invention is toprovide a composition and method for the safe, convenient and effectiveway of administering the useful drugs oxybutynin to a patient in need ofsuch treatment. The method comprises intranasal administration of aneffective amount of oxybutynin for the treatment of overactive bladderwith symptoms of urinary urgency, frequency or urge incontinence andother disorders.

[0016] Nasal drug administration serves as an alternative route of drugadministration. It has been shown that most drugs administered nasallyproduce plasma levels similar to those following intravenousadministration (Hussain, et al., J. Pharm. Sci. 69:1240, 1980;Bawarshi-Nassar et al., J. Pharm. Pharmacol. 41: 214, 1989; Hussain, etal., J. Pharm. Sci. 68: 1196, 1979). The nasal delivery route is a veryuseful method of drug administration, which frequently improves drugbioavailability by direct absorption into the circulation avoidinghepatic first-pass metabolism and destruction in the gastrointestinaltract following oral delivery of drug (Chien, et al., Marcel Dekker, NewYork, 1989.).

[0017] The objective of the present inventions is to improve oxybutyninbioavailability by administering oxybutynin via the nasal route in orderto reduce the dose required for its beneficial effect. Intranasaloxybutynin delivery will improve drug bioavailability by directabsorption into the circulation avoiding extensive hepatic first-passmetabolism which significantly lowers the plasma concentrations ofoxybutynin administered orally. Therefore, small doses of oxybutynin canbe administered which will results in fewer side effects, and the drugwill be more tolerable and more effective in treating patients sufferingfrom overactive bladder with symptoms of urinary urgency, frequency orurge incontinence and other disorders described above. Additionally, asoxybutynin is heavily metabolized by the liver, administration by thenasal route will help to reduce drug-drug interactions with other drugsthat are also extensively metabolized by the liver.

[0018] Nasal administration of oxybutynin would be expected by theApplicants to increase oxybutynin blood levels with a concomitantdecrease in blood levels of their major metabolitesN-desethyloxybutynin. This expected increase by Applicant in drugconcentration ratio of unchanged oxybutynin to metabolite in thesystemic circulation is even more significant in light of studies whichindicate the association of the major metabolites N-desethyloxybutyninwith significant side effects.

[0019] In addition, nasal oxybutynin administration is easy andconvenient. Furthermore, in many situations it has already been shownthat the onset and extent of drug delivery after intranasaladministration is comparable to the same drug and dose being givenintravenously. Therefore, intranasal delivery of drug for treatment ofoveractive bladder with symptoms of urinary urgency such as oxybutynincould be used in those situations where a rapid or intermittent drugeffect is desired.

[0020] In certain embodiments, the invention is directed to a method ofproviding oxybutynin therapy to a patient in need thereof comprisingintranasally administering an effective amount of oxybutynin or apharmaceutically acceptable salt thereof to said patient andcompositions thereof. Preferably, the oxubutynin is administered with apharmaceutically acceptable carrier which can be in the form of, e.g. asolution, suspension, gel, ointment, lotion, semi-solid, vaporizablecarrier, a powder and combination thereof. In certain embodiments, thecarrier can provide a sustained release of the drug.

[0021] In certain embodiments, the invention is directed to a method ofreducing side effects associated with oxybutynin therapy comprisingadministering a therapeutically effective amount of oxybutyninintranasally, the intranasal administration reducing side effectsassociated with the oral administration of an equivalent dose ofoxybutynin. In certain embodiments, the intranasal administrationreduces side effects by reducing the formation of the N-desethylmetabolite of oxybutynin as compared to an equivalent dose of oraloxybutynin.

[0022] In certain embodiments, the ratio of the plasma concentration ofthe desmethyl metabolite of oxybutynin after said intranasaladministration to the plasma concentration of the N-desethyl metaboliteof oxybutynin after the oral administration is less than about 1:5, lessthan about 1:10 or less than about 1:20.

[0023] In certain embodiments, the ratio of the plasma concentration ofthe N-desethyl metabolite said nasal administration to the plasmaconcentration of oxybutynin is less than about 2:1, less than about 1:1,less than about 0.75:1, or less than about 0.55:1.

[0024] In certain embodiments, the bioavailability of the of theintranasal oxybutynin is increased as compared to an equivalent dose oforal oxybutynin. In preferred embodiments, the ratio of the AUC afterintranasal oxybutynin to AUC of oxybutynin after an equivalent dose oforal oxybutynin is at least 2:1 or at least 4:1, and preferably at least8:1 or at least 10:1. In certain embodiments, the ratio is based on theabsolute AUC and other embodiments the AUC is measured at 2 hours afteradministration. The ratios are also based on the oral oxybutynin beingadministered as a solution or a tablet

[0025] With the foregoing and other objects, advantages and features ofthe invention that will become hereinafter apparent, the nature of theinvention is further explained in the following detailed description ofthe preferred embodiments of the invention and in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1. depicts the structures of oxybutynin and its majormetabolite N-desethyloxybutynin.

[0027]FIG. 2 is a bar graph of oxybutynin (5 mg/kg) bioavailability inrats following nasal and oral administration, relative to theintravenous administration (100%). Data presented as mean±SEM (n=4).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0028] Orally administered oxybutynin currently available on the marketshow extensive first pass metabolism with a ten-fold variation betweensubjects. Thus, the present inventions have discovered a novelcomposition and method for the delivery of oxybutynin to a patient inneed of such treatment, comprising the intranasal administration ofoxybutynin. This composition and method offers significant clinicaladvantages over the prior art. More specifically, the inventors soughtto provide a safe, effective, fast and convenient treatment foradministering oxybutynin to a patient in need of such treatment, whichcomprises the administration of oxybutynin intranasally, thus avoidingthe side-effects and other disadvantages associated with oral dosageforms. Specifically, smaller doses of oxybutynin can be administeredthrough the nasal route, thus resulting in rapid onset of action, fewerside effects and reducing drug-drug interactions. By using thecomposition and method of the present invention, the drug will becomemore tolerable and more effective in treating patients suffering fromoveractive bladder with symptoms of urinary urgency, frequency or urgeincontinence.

[0029] Intranasal administration of oxybutynin is as effective as oraladministration, but may be conveniently and painlessly self-administeredby the patient, and at lower doses and faster onset of action comparedto oral dosage forms, thereby allowing a decreased incidence of sideeffects and decreased incidence of drug-drug interactions and fasteronset of action compared to the oral administration.

[0030] As used in the present invention, the term “oxybutynin” will beunderstood to refer to either (R)-oxybutynin, (S)-oxybutynin, or aracemic mixture of (R)- and (S)-oxybutynin.

[0031] According to the present invention, oxybutynin and other relatedcompounds and their metabolites may be administered either as a freebase, or in the form of a pharmaceutically acceptable salt thereof.Pharmaceutically acceptable salts of an acid group or an amino groupinclude, but are not limited to, salts of both inorganic or organicacids, for example: acetic, fumaric, benzoic, ascorbic, pamoic, lactic,tartaric, maleic, isothionic, lactobionic, succinic, oxalic, propionic,citric, gluconic, aspartic, stearic, palmitic itaconic, glycolic,p-aminobenzoic, glutamic, salicylic, bismethylenesalicylic,methanesulfonic, ethandisulfonic, ethanesulfonic, benzenesulfonic,cyclohexylsulfamic, p-tolylsulfonic, hydrobromic, hydrochloric,sulfuric, phosphoric, nitric, and sulfamic acids. In a particularlypreferred embodiment, the pharmaceutically acceptable salt is oxybutyninchloride because of good water solubility.

[0032] A still further aspect of this invention is a pharmaceuticalcomposition of matter that comprises oxybutynin as described above,and/or pharmaceutically acceptable salts thereof, and at least onepharmaceutically acceptable carrier suitable for nasal administration.

[0033] For therapeutic use for overactive bladder with symptoms ofurinary urgency, frequency or urge incontinence and other disordersdescribed above, oxybutynin, or its salt can be convenientlyadministered in the form of a pharmaceutical composition containingoxybutynin, its salt, and a pharmaceutically acceptable carrier thereof.Suitable carriers are well known to those skilled in the art and varywith the desired form and mode of administration of the pharmaceuticalcomposition. Typically, the carrier may be a liquid, solution,suspension, gel, ointment, lotion, semi-solid, or vaporizable carrier,or combinations thereof. In a preferred embodiment, the carrier is apharmaceutically acceptable aqueous carrier. Such compositions areprepared in accordance with accepted pharmaceutical procedures, forexample, as described in Remington's Pharmaceutical Sciences, seventeenedition, ed. Alfonso R. Gennaro, Mack Publishing Company, Easton, Pa.Eighteenth edition (1990), which is hereby incorporated by reference.The drug can also be in powder form without the need for furtherexcipient.

[0034] The compound of the invention or its salt may be formulatedtogether with the carrier into any desired unit dosage form. Unit dosageforms such as solutions, suspensions, and water-miscible semisolids areparticularly preferred.

[0035] Each carrier must be “acceptable” in the sense of beingcompatible with the other ingredients in the formulation and notinjurious to the patient. The carrier must be biologically acceptableand inert. To prepare formulations suitable for intranasaladministration, solutions and suspensions are sterilized and arepreferably isotonic to blood.

[0036] The formulations may conveniently be presented in unit dosageform and may be prepared by any method known in the art. Such methodsinclude the step of bringing the active ingredient into association withthe carrier which itself may encompass one or more accessoryingredients. In general, the formulations are prepared by uniformly andintimately bringing into association the active ingredient with liquidcarriers or finely divided solid carriers or both, and then if necessaryshaping the product. Various unit dose and multidose containers, e.g.,sealed ampules and vials, may be used, as is well known in the art (seeRemington's Pharmaceutical Sciences, seventeenth edition, ed. Alfonso R.Gennaro, Mack Publishing Company, Easton, Pa. Eighteenth edition, 1990).For example, the oxybutynin can be administered into the nasal passagesby means of a simple dropper a dispensing tube from which the contentsare expelled drop by drop by means of air pressure provided by amanually powered pump, e.g., a flexible rubber bulb, attached to oneend. Fine droplets and sprays can be provided by a manual orelectrically powered intranasal pump dispenser or squeeze bottle as wellknown to the art, e.g., that is designed to blow a mixture of air andfine droplets into the nasal passages.

[0037] In addition to the ingredients particularly mentioned above, theformulations of this invention may also include other agentsconventional in the art for this type of pharmaceutical formulation. Forexample, the nasal formulation can provide a sustained release of thedrug in order for e.g., once or twice daily. Suitable sustained releasematerials include cellulosic derivatives which adheres to the nasalmucosa, as described in EP 205282, hereby incorporated by reference.

[0038] The present invention is also directed to a method of treatingoveractive bladder with symptoms of urinary urgency, frequency or urgeincontinence, and to a method for treating other disorders in a patientby treating that patient with an effective amount of oxybutyninintranasally. According to the present invention, the term “patient”will encompass any mammal requiring treatment with oxybutynin,particularly a human patient suffering from overactive bladder withsymptoms of urinary urgency, frequency or urge incontinence, or humanpatient suffering from other disorders requiring such treatment.

[0039] The dosage of oxybutynin or pharmaceutically acceptable saltsthereof in the compositions of the invention will vary depending onseveral factors, including, but not limited to, age, weight, and speciesof patient, the general health of the patient, the severity of thesymptoms, whether the composition is being administered alone or incombination with other agents, the incidence of side effects and thelike. The desired dose may be administered as 1 to 6 or more subdosesadministered at appropriate intervals throughout the day. The compoundsmay be administered repeatedly over a period of months or years. Higherand lower doses may also be administered. For example, a dose ofoxybutynin can be from 0.01 mg per dose to 50 mg per dose, e.g., 0.5 mg,1 mg, 1.5 mg, 2 mg, 2.5 mg, 3 mg 5 mg, 7.5 mg 10 mg or 15 mg.

[0040] The daily dose may be adjusted taking into account, for example,the above-identified variety of parameters. Typically, oxybutynin or itsderivatives may be administered in an amount of up to about 50 mg/day.However, other amounts may also be administered depends on the relativepotency of the basic compound, the specific biological activity and theconditions of the patient.

[0041] To achieve good plasma concentrations, the oxybutynin may beadministered, for instance, by intranasal administration of anapproximate 0.1 to 1M solution of the active ingredient, optionally insaline.

[0042] While it is possible for the active ingredient to be administeredalone, it is preferably present as a pharmaceutical formulation. Theformulations of the present invention comprise of at least one activeingredient, as defined above, together with one or more acceptablethereof and optionally other therapeutic agents.

[0043] The above method may be practiced by administration of thecompounds by themselves or in a combination with other activeingredients in a pharmaceutical composition. Other therapeutic agentssuitable for use herein are any compatible drugs that are effective bythe same or other mechanisms for the intended purpose, or drugs that arecomplementary to those of the present agents, e.g., otheranticholinergic or any other agents used for disorders described above.The compounds utilized in combination therapy may be administeredsimultaneously, in either separate or combined formulations, or atdifferent times than the present compounds, e.g., sequentially, suchthat a combined effect is achieved. The amounts and regime ofadministration will be adjusted by the practitioner, by preferablyinitially lowering their standard doses and titrating the resultsobtained. The therapeutic method of the invention may be used inconjunction with other therapies as determined by the practitioner.

[0044] Having now generally described this invention, the same will bebetter understood by reference to certain specific examples, which areincluded herein for purposes of illustration only and are not intendedto be limiting of the invention or any embodiment thereof, unless sospecified.

EXAMPLE 1 In Vivo Nasal Delivery of Oxybutynin

[0045] Surgical Procedures:

[0046] The nasal absorption of oxybutynin was studied using an in vivotechnique described previously (1). Male Sprague-Dawley rats ( bodyweight 250±25 gm) were used in these studies. Animals were fastedovernight prior to experimentation. Surgical procedures were performedunder equithesin anesthesia (3 ml/kg, i.p.). An incision was made in theneck, and the trachea cannulated with polyethylene tubing (PE-260). Aclosed end tube was inserted through the esophagus to the posterior partof the nasal cavity to prevent drug from entering the esophagus. Thenasopalatine passage was then closed with an adhesive agent to preventdrainage of the drug from the nasal cavity to the mouth.

[0047] Blood samples were collected from a cannula inserted into thefemoral artery. For intravenous drug administration, the jugular veinwas cannulated.

[0048] Experimental Procedure:

[0049] Solutions of oxybutynin hydrochloride (5 mg/kg/100 μl) wereprepared in normal saline and administered through the right nostrilusing a microsyringe. For oral administration, rats received an aqueoussolution of oxybutynin hydrochloride (5 mg/kg) administered by gavagetube. For intravenous (i.v.) administration, the same dose of oxybutyninwas injected into the jugular vein (1 ml/kg body weight). Blood samplesafter oxybutynin administration were collected before and at 0, 5, 10,20, 40 and 60 min after drug administration, centrifuged, and serumremoved and stored (−70° C.) until analysis.

[0050] Differences in the plasma oxybutynin or N-desethyloxybutyninconcentrations between i.v., oral, and nasal delivery routes werecompared using the Student's t test.

[0051] Extraction and HPLC Analysis of Oxybutynin and Its Metabolite:

[0052] Analysis of oxybutynin and its metabolites N-desethyloxybutyninwere performed using HPLC as described by Buyse et al. (2). Extractionof standards for calibration curve and plasma samples were performed asdescribed previously by Hughes et al. (3).

[0053] Oxybutynin and its metabolite (N-desethyloxybutynin) wereanalyzed using a reverse-phase column (25 cm×46 mm I.D.) and eluted withmobile phase consisting of 50% acetonitrile in 10 nmol/L potassiumphosphate buffer, pH 6.3. The mixture was filtered and degassed prior touse. The flow rate was 0.7 ml/min, and the effluent was monitored with adual UV detector system at 210 nm.

[0054] All determinations were performed by calculating the area ratiosof each compound to the internal standard. Unknown amounts weredetermined from calibration curves run with each day's unknown analysis.

[0055] Results and Discussion

[0056] Our data shows a large improvement (˜10 fold increase) in thebioavailability of oxybutynin after intranasal administration comparedto orally administered oxybutynin. Bioavailability of orallyadministered oxybutynin was very low, approximately 9%, due to extensivefirst pass metabolism (FIG. 2). The high bioavailability of intranasaloxybutynin (90%) indicates circumvention of the first-pass effect. Thisimprovement in oxybutynin bioavailability means significantly lessamount of oxybutynin will be needed for intended treatment. In additionto improvement in bioavailability, the rapid absorption of theintranasally administered oxybutynin allows the drug into the systemiccirculation almost instantly (t_(max)=10 min, Table 1). The t_(max) oforally administered oxybutynin was approximately 30-40 min. The orallyadministered oxybutynin in our experiment was delivered as a solution ofoxybutynin in water. We will expect the t_(max) of orally administeredoxybutynin as a solid dosage form (tablet) currently available in themarket will take longer than 40 min. This is another significantadvantage of nasally administered oxybutynin.

[0057] The high bioavailability of intranasal oxybutynin is dependentupon the relative rates of intranasal absorption versus elimination ofthe formulated dose from the nasal cavities by mucociliary clearance anddrainage. Both absorption and drainage can be affected by the uniquephysiochemical characters of the compound under investigation and theformulation used (4, 5). Our data prove that the physiochemicalproperties of oxybutynin makes it an excellent candidate drug for nasaldelivery which presents a novel and unobvious drug characteristic. TABLE1 Concentration ratio of oxybutynin and its metabolite, N-desethyloxybutynin in rat over 1 hr following an oral or intranasal doseof oxybutynin (5 mg/kg). Data expressed as mean ± SEM. Results generatedfrom 4 rats per group. Ratio N-desethyl- N-desethyloxybutynin/Oxybutynin oxybutynin Oxybutynin Oral 12.39 ± 2.1 t_(max) 40 min 1.1 hAUC_(0-2 h) 180 ± 53 2230 ± 479  Nasal   0.55 ± 0.137 t_(max) 10 min 1.6h AUC_(0-2 h) 1770 ± 190 970 ± 179

[0058] Since one of the major metabolites of oxybutynin,N-desethyloxybutynin is associated with adverse effects (dry mouth,nausea, constipation . . . etc.) which leads to decrease patientcompliance with the treatment (2), we also measured the concentration ofthis metabolite, (N-desethyloxybutynin), in plasma following oral ornasal administration of oxybutynin (5 mg/kg) and to investigate whetherthe level of this metabolite could be reduced by nasal delivery of thedrug. The relative plasma levels of oxybutynin and N-desethyloxybutyninare shown in Table 1. The data in Table 1 are presented as a ratio ofthe oxybutynin major metabolite, N-desethyloxybutynin, to parentcompound oxybutynin, to emphasize the benefit of comparing nasal vs oralroutes of administration in reducing metabolite levels (high metabolitelevels associated with poor clinical outcome). Following oraladministration of oxybutynin to rats, the concentration ofN-desethyloxybutynin was approximately 12 fold greater than that of theparent compound oxybutynin in plasma. Following nasal administration ofoxybutynin to rats, the plasma concentration of N-desethyloxybutynin wasaround half (0.55) of that of oxybutynin. This is a new finding and aparticularly important factor in developing appropriate dosage forms forhuman use in which less of the oxybutynin will be transformed toN-desethyloxybutynin. It has been reported in human that higher plasmametabolite concentrations N-desethyloxybutynin is associated withadverse effects and decreased patient compliance with the treatment (2).Therefore nasal delivery of oxybutynin will avoid first pass metabolismof oxybutynin and will allow the drug to be distributed to the site ofaction prior to metabolism to N-desethyloxybutynin. Indeed our data withthe nasal delivery of oxybutynin showed a significant reduction in thelevel of N-desethyloxybutynin. Our findings with the nasal delivery ofoxybutynin will be have important impact when applied to humans.

[0059] In conclusion, the present data demonstrates that improvedbioavailability and reduced first-pass metabolism of intranasaloxybutynin results in a significantly lower concentration ratio ofN-desethyloxybutynin over the parent compound oxybutynin than isobserved following oral administration, that will explain the clinicallyrelevant reduction of side effects that characterize intranasaltreatment. Furthermore, the rapid absorption of oxybutynin through thenasal cavity provides rapid onset of action of the drug, an almostinstant therapeutic effect which is a major advantage over the oraldelivery system. In addition nasal delivery of oxybutynin will improveand reduce the interindividual variability that has been reportedpreviously after oral intake; genetic polymorphism, with some patientsbeing poor metabolizers, has been suggested to explain the variation.

EXAMPLE 2 Nasal Spray Solution

[0060] Oxybutynin chloride 250 mg Isotonic Saline q.s. 10 ml

[0061] Oxybutynin is dissolved in sterile isotonic saline and the pHadjusted to 7.4. The solution is placed in a nasal administratordesigned to deliver 0.1 ml of spray for each application. One spray ineach nostril will deliver a total of 5 mg of oxybutynin.

EXAMPLE 3 Nasal Gel (Aqueous)

[0062] Oxybutynin 250 mg Methocel  3 gm Water 100 gm

[0063] Approximately 7 gm of water is heated to 80° C., and the methocelis dispersed in it with stirring. The oxybutynin is dissolved in 30 gmof water at 80° C., and the solution is mixed with the methoceldispersion. The resultant mixture is allowed to stand at roomtemperature for 3 hours. The gel is placed in an ointment tube equippedwith a fine orifice and is applied in the nasal nares with a finger orcotton tipped applicator.

EXAMPLE 4 Nasal Spray Solution

[0064] Oxybutynin chloride 50 mg Isotonic Saline 10 ml

[0065] Oxybutynin is dissolved in sterile isotonic saline and the pHadjusted to 7.4. The solution is placed in a nasal administratordesigned to deliver 0.1 ml of spray for each application. One spray ineach nostril will deliver a total of 1 mg of oxybutynin.

EXAMPLE 5 Nasal Gel (Aqueous)

[0066] Oxybutynin 50 mg Methocel  3 gm Water 100 gm

[0067] Approximately 7 gm of water is heated to 80° C., and the methocelis dispersed in it with stirring. The oxybutynin is dissolved in 30 gmof water at 80° C., and the solution is mixed with the methoceldispersion. The resultant mixture is allowed to stand at roomtemperature for 3 hours. The gel is placed in an ointment tube equippedwith a fine orifice and is applied in the nasal nares with a finger orcotton tipped applicator.

What is claimed is:
 1. A method of providing oxybutynin therapy to a patient in need thereof comprising intranasally administering an effective amount of oxybutynin or a pharmaceutically acceptable salt thereof to said patient.
 2. The method of claim 1 wherein said oxubutynin is administered with a pharmaceutically acceptable carrier.
 3. The method of claim 2 wherein the carrier is selected from the group consisting of a solution, suspension, gel, ointment, lotion, semi-solid, vaporizable carrier, a powder and combination thereof.
 4. The method of claim 1 wherein said oxybutynin is selected from the group consisting of oxybutynin base, R-oxybutynin base, S-oxybutynin base, pharmaceutically acceptable salts thereof and mixtures thereof.
 5. A pharmaceutical composition comprising oxybutynin and a pharmaceutically acceptable carrier suitable for nasal administration.
 6. The composition of claim 5 wherein the carrier provides a sustained release of the oxybutynin.
 7. A method of reducing side effects associated with oxybutynin therapy comprising administering a therapeutically effective amount of oxybutynin intranasally, said intranasal administration reducing side effects associated with the oral administration of an equivalent dose of oxybutynin.
 8. The method of claim 7 wherein said intranasal administration reduces side effects by reducing the formation of the N-desethyl metabolite of oxybutynin as compared to an equivalent dose of oral oxybutynin.
 9. The method of claim 8 wherein the ratio of the plasma concentration of the desmethyl metabolite of oxybutynin after said intranasal administration to the plasma concentration of the N-desethyl metabolite of oxybutynin after said oral administration is less than about 1:5.
 10. The method of claim 9 wherein said ratio is less than about 1:10.
 11. The method of claim 9 wherein said ratio is less than about 1:20.
 12. The method of claim 7 wherein the ratio of the plasma concentration of the N-desethyl metabolite said nasal administration to the plasma concentration of oxybutynin is less than about 2:1.
 13. The method of claim 12 wherein the ration is less than about 1:1.
 14. The method of claim 12 wherein the ration is less than about 0.75:1.
 15. The method of claim 12 wherein the ration is less than about 0.55:1.
 16. A method of increasing the bioavailability of oxybutynin comprising administering intranasally the composition of claim 5 whereby the bioavailability of the intranasal oxybutynin is increased as compared to an equivalent dose of oral oxybutynin.
 17. The method of claim 16 wherein the ratio of the AUC of oxybutynin after intranasal oxybutynin to AUC of oxybutynin after an equivalent dose of oral oxybutynin is at least 2:1.
 18. The method of claim 17 wherein said ratio is at least 4:1.
 19. The method of claim 17 wherein said ratio is at least 8:1.
 20. The method of claim 17 wherein said ratio is at least 10:1. 